[Imaging and quantification of corneal neovascularization]

Engineering Matrix-Free Drug Protein Nanoparticles with Promising Penetration through Biobarriers for Treating Corneal Neovascularization

Protein drugs have been widely used in treating various clinical diseases because of their high specificity, fewer side effects, and favorable therapeutic effect, but they greatly suffer from their weak permeability through tissue barriers, high sensitivity to microenvironments, degradation by proteases, and rapid clearance by the immune system. Herein, we disrupted the standard protocol where protein drugs must be delivered as the cargo via a delivery system and innovatively developed a free entrapping matrix strategy by simply mixing bevacizumab (Beva) with zinc ions to generate Beva-NPs (Beva-Zn2+), where Beva is coordinatively cross-linked by zinc ions with a loading efficiency as high as 99.2% ± 0.41%. This strategy was universal to generating various protein NPs, with different metal ions (Cu2+, Fe3+, Mg2+, Sr2+). The synthetic conditions of Beva-NPs were optimized, and the generated mechanism was investigated in detail. The entrapment, releasing profile, and the bioactivities of released Beva were thoroughly studied. By using in situ doping of the fourth-generation polyamindoamine dendrimer (G4), the Beva-G4-NPs exhibited extended ocular retention and penetration through biobarriers in the anterior segment through transcellular and paracellular pathways, effectively inhibiting corneal neovascularization (CNV) from 91.6 ± 2.03% to 13.5 ± 1.87% in a rat model of CNV. This study contributes to engineering of protein NPs by using a facile strategy for overcoming the weaknesses of protein drugs and protein NPs, such as weak tissue barrier permeability, low encapsulation efficiency, poor loading capacity, and susceptibility to inactivation.

Imaging of vascular abnormalities in ocular surface disease

The vascular system of the ocular surface plays a central role in infectious, autoimmune, inflammatory, traumatic and neoplastic diseases. The development, application, and monitoring of treatments for vascular abnormalities depends on the in vivo analysis of the ocular surface vasculature. Until recently, ocular surface vascular imaging was confined to biomicroscopic and color photographic assessment, both limited by poor reproducibility and the inability to image lymphatic vasculature in vivo. The evolvement and clinical implementation of innovative imaging modalities including confocal microscopy, intravenous, and optical coherence tomography-based angiography now allows standardized quantitative and functional vascular assessment with potential applicability to automated analysis algorithms and diagnostics.

Evaluation of Clinical and Histological Outcomes of Adipose-Derived Mesenchymal Stem Cells in a Rabbit Corneal Alkali Burn Model

To assess effects of adipose-derived mesenchymal stem cells (AMSCs) in corneal alkali injuries in an experimental animal model. Twenty white New Zealand rabbits were included in the study. The animal models were randomly divided into 2 groups. Rabbits in the AMSC group (n = 10) received an intrastromal, a subconjunctival injection, and topical instillation of 0.5 ml totally of phosphate-buffered saline (PBS) containing 2 × 10⁶ AMSCs. In the control group (n = 10), rabbits received only 0.5 ml of PBS using the same methods. A masked investigator measured the corneal sensation, anterior chamber Inflammation (ACI), and conjunctival congestion. Additionally, a blind histological and immunohistochemical evaluation was made. In the AMSC group, the central corneal sensation was increased whereas ACI and conjunctival congestion were reduced compared to the control group in the 28 days of follow-up (p < 0.05). A statistically significant difference (p < 0.05) was noted between the two groups as recorded in the above parameters. Histological analysis showed that pathological vascularization was markedly reduced in the AMSC group which was consistent with the absence of factor VIII in the immunohistochemistry sections. There is a trend towards improved clinical outcomes including corneal sensation as well as acceleration in the restoration of normal corneal architecture in corneal alkali burns treated with AMSCs, results that support the need for further research in the field.

Protective Effect of TLR4 Ablation against Corneal Neovascularization following Chemical Burn in a Mouse Model

PURPOSE

To determine whether Toll-like receptor 4 knockout protects mice from corneal neovascularization following chemical injury compared to wild-type (WT) mice.

METHODS

A chemical burn (75% silver nitrate, 25% potassium nitrate) was created under anesthesia in the central right cornea of 32 WT and 31 Toll-like receptor 4 knockout mice. Corneal neovascularization was evaluated at 3, 4, 6, 8, 10, and 35 days after injury using digital photography, fluorescein angiography, gelatin perfusion with fluorescence vascular imaging, immunofluorescence staining, and molecular analysis.

RESULTS

There was no significant between-group difference in relative corneal burn area at 10 days after injury (39.0 ± 2.4% vs. 38.8 ± 9.8%, respectively). Neovascularization was detected in all corneas in vivo and perfusion was detected by fluorescence vascular imaging, reaching maximum area on day 10. The relative area of neovascularization was significantly smaller in the knockout than the WT mice on days 6 (33.3 ± 4.2% vs. 46.8 ± 7.4%, respectively, p = 0.005) and 8 (36.6 ± 1.1% vs. 52.2 ± 6.4%, respectively, p = 0.027), although neovascularization was intensive in both groups. In line with the immunostaining findings of angiogenesis and inflammatory infiltration of damaged corneas, molecular analysis (performed on day 3) revealed elevated expression levels of angiogenesis-related genes (vascular endothelial growth factor, VEGFR2, VEGFR1) and inflammation-related genes (CD45 and TGFβ1) in the WT mice. The knockout mice had higher TNF-α expression than the WT mice.

CONCLUSION

In a mouse corneal chemical burn model, lack of Toll-like receptor 4 expression did not completely inhibit angiogenesis, but did have a relative effect to reduce neovascularization as compared to the WT.

Tissue and cellular characterisation of nucleolin in a murine model of corneal angiogenesis

PURPOSE

Corneal neovascularisation (CNV), with consequent loss of transparency, is due to an imbalance of proangiogenic factors. Cell-surface nucleolin (NCL) has been associated with neo-angiogenesis. There are studies identifying NCL translocation from nucleus to the cell surface, which is essential for endothelial cell proliferation. To find the possible role of NCL in the generation of corneal neovessels, the aim of this study is to characterise the NCL presence and cell-localisation in non-injured corneas, as well as to describe the changes in NCL cell and tissue localisation in CNV, and to analyse the effect of bevacizumab on NCL cellular and tissular distribution.

METHODS

Suture-induced CNV was performed in mice. The corneal tissues were obtained and the histological and co-immunofluorescence assays were performed using different proteins, such as CD31, cadherin and isolectin B4. To determine the possible role of VEGF in NCL presence and localisation in our CNV model, bevacizumab was concomitantly used.

RESULTS

Nucleolin was principally observed in the nucleus of the basal epithelial cells of normal corneas. Interestingly, angiogenesis-induced changes were observed in the localisation of NCL, not only in tissue but also at the cellular level where NCL was extranuclear in epithelial cells, stromal cells and neovessels. In contrast, these changes were reverted when bevacizumab was used. Besides, NCL was able to stain only aberrant corneal neovessels in comparison with retinal vessels.

CONCLUSIONS

NCL mobilisation outside the nucleus during angiogenesis could have a possible role as a proangiogenic molecule in the corneal tissue.

[Corneal neovascularisation treatments compared: Subconjunctival bevacizumab injections and/or photodynamic therapy]

PURPOSE

To evaluate and compare the efficacy of subconjunctival bevacizumab injections alone, photodynamic therapy alone and combined treatments for reduction of corneal neovascularization.

METHODS

This study was conducted as a prospective case series. A total of seven eyes of 7 patients with corneal neovascularization caused by ocular surface disorders including fungal infectious keratitis and penetrating keratoplasty were included in the study. Patients were randomized into the three following groups: patients in group A received a single subconjunctival injection of 10mg (0.4mL) of bevacizumab, patients in group B were treated with photodynamic therapy with verteporfin (6mg/m(2)) to the neovascularized area and those in group C received a subconjunctival injection of bevacizumab and photodynamic therapy 7 days later. Morphological changes in neovascularization were evaluated over 6 months using slit-lamp biomicroscopy and digital corneal photography. A computer-assisted semi-automatic analysis of the area of corneal neovascularization was performed with Image J software.

RESULTS

Recession of corneal vessels was observed in all eyes at 1 month post-treatment. The neovascularized surface area in all groups combined showed a decrease in the first month after treatment and this decrease continued up to the 6th month. The surface area of corneal neovascularization decreased by 34.05±8.28% in group A (subconjunctival injection of bevacizumab), by 42.06±28.36% in group B (photodynamic therapy with verteporfin) and by 51.67±18.93% in group C (combined subconjunctival injection of bevacizumab and photodynamic therapy). A combined treatment consisting of a subconjunctival injection followed by a PDT session 7 days later might be more effective for the treatment of corneal neovascularisation. No serious local or systemic adverse events were observed.

CONCLUSIONS

Our medium-term results suggest that combined subconjunctival injection of bevacizumab and photodynamic therapy with verteporfin might be used safely and effectively to reduce corneal neovascularization surface. This combined therapy may show a tendency toward greater efficacy than the individual monotherapies. Controlled prospective randomized multicentric trials with a larger sample size are necessary to assess long-term efficacy and to confirm these results.